As is generally well known, air filters are used extensively to prevent particulate impurities such as dust and dirt from entering into the combustion chambers of engines. A typical air filter is annular in construction and has a filtering medium which is incorporated into the cylindrical side wall and which allows for passage of air but traps the particulates on its outer surface. When the particulate build-up becomes significant, the air flow through the filtering medium is restricted causing abnormal operation of the combustion engine that increases operating costs and may potentially result in engine failure.
On passenger-type vehicles, it takes a relatively long period of time for the air filter to accumulate significant amount of particulate which will restrict air flow and, therefore, these air filters are replaced infrequently.
On heavy off-road and over the road vehicles, it is common for air filters to accumulate undesirable amount of particulate in a matter of days. Thus, these air filters need frequent attention to maintain the required air flow. However, air filter replacement is usually prohibitive due to cost of the new air filter requiring the operators of such vehicles to periodically clean air filters. One cleaning method is to repeatedly strike the air filter against a rigid structure to dislodge the particulate. However, it has been found that such method does not remove all accumulated particulate. Another method involves use of an air hose with the nozzle inserted into the inner aperture or cavity of the air filter. However, the air is discharged through the nozzle at higher than desirable pressure capable of damaging the filtering medium and requires greater than desirable effort and concentration by the operator to adequately clean the air filter without damaging filtering medium.
Prior to the present invention, efforts have been made to alleviate difficulties in cleaning air filters.
U.S. Pat. No. 5,078,763 issued to Blount-Gillette discloses one type of a portable air filter cleaning device that includes a bottom plate member having a flat upper surface, an apertured vertical column connected to a high pressure air hose and fixed to the bottom member, and a top plate member, removable from the vertical column, having a flat bottom surface, where an annular filter is placed around the vertical column and top plate member is placed onto the vertical column, sealing the filter between the top plate member and the bottom plate member. Air is then forced into the vertical column, exiting through the apertures and through the filter itself, forcing any accumulated particles off the surface of the filter. The disadvantage of this prior art device is in that the vertical column has a fixed length which is not adequate to properly clean all air filters presently in use.
U.S. Pat. No. 3,958,298 issued to Fell discloses another type of the portable filter cleaning device that includes a housing and an upper member. The air filter to be cleaned is inserted between the housing and the upper member. The upper member is provided with a vertically depending rotatable pipe means provided with radially directed nozzles. The pipe means is also provided with a pair of nozzles directed at an angle to the radial to provide a rotary movement to the pipe means. The air filter cleaner may be operated from air compressors readily available on the job site, such as compressors on the heavy construction equipment itself. However, it has been found that rotational speed of the pipe means is dependent on the inner diameter of the air filters with air filters having smaller diameter being cleaned better than air filters having larger diameter. Furthermore, the prior art device of Fell is disadvantaged by the fixed length of the pipe means.
In U.S. Pat. No. 6,588,057, McMahon discloses yet another type of the portable air filter cleaning device that includes en elongated, readily gripable handle having a through bore and a connector at one end for coupling to an air supply hose, and a rotary head is rotatably mounted on the other end of the handle. The rotary head has an internal air distribution chamber with small outlet openings in its outer peripheral wall for spraying air from the chamber. Rotor outlet passageways in the peripheral wall are arranged at an angle to cause the head to spin in a turbine-like fashion when air flow is directed from the chamber and out through the passageways. The rotating head sprays air outwardly across the surface of an air filter unit to dislodge dirt from filter paper in a filter unit. McMahon overcomes the disadvantage of the fixed length member of Blount-Gillette and Fell in that the head is manually moveable along the entire length of the air filter, however, greater then desirable effort is required to clean each air filter due to the axial movement of the rotary head. Another disadvantage of this prior art device is in that the operator is burdened by the responsibility to control the pressure applied by the rotating head onto the filtering medium. Yet another disadvantage of this prior art air filter cleaning device is that the ends of the air filter are not sealed during cleaning process thus wasting the supplied air pressure and increasing the time required to clean the filter.
Therefore, there is a need for an improved portable apparatus for equally cleaning air filters of various lengths and diameters and for controlling the amount of air pressure applied to the inner surface of the filtering medium.